Polyurethane foams have been extensively used for various applications primarily due to the excellent and diverse physical properties of polyurethane foams. Polyurethane foams are available having soft and resilient characteristics rendering them useful in pillows and blankets. Other polyurethane foams have moderate load-bearing characteristics and as a result are widely used, for example, as seatings in furniture and as fillings for mattresses. Still other polyurethane foam compositions are relatively firm and find application in men's and women's apparel, packaging, thermal and acoustical insulation, and carpet underlay. The versatility and quality of the products that can be manufactured from polyurethane foam are related to the advances that have been made in the chemistry of raw materials used in the foams and in the technology that has evolved in the formulation and processing of materials into satisfactory and needed products.
In recent years it has become desirable or necessary to increase the flame retardancy of foams and/or to prevent the dripping of the hot melt of a foam product when subjected to high heat. These characteristics are collectively referred to for purposes of the present invention as the "combustion retardency" of the foam. In rendering foams combustion retardant, various additives have been added to the polyurethane foams, including inorganic and organic fillers. Conventionally, these additives were incorporated into the foam at the time of the initial foaming. However, in commonly assigned U.S. Pat. No. 4,438,220 polyurethane foam products are described comprising a foam filled with a foam and containing large amounts of combustion retardant materials. The foam products of the '220 patent are prepared by foaming a polyurethane foam-forming diisocyanate and polyol around pre-formed polyurethane foam chips in admixture with solid combustion retardant materials. According to the '220 patent, it was found that foam products having larger amounts of inorganic flame-retardant materials, and accordingly greater combustion retardancy characteristics, could be fabricated when using the foam chips bonded together with new foam, than was possible in a conventional, in situ, foaming process. The products obtained according to the '220 patent have improved physical characteristics in comparison with the conventionally foamed combustion-retardant foams, rendering them particularly suitable for use in furniture upholstery, cushioning applications including in mattresses, and where special properties were required.
Commonly assigned U.S. Pat. No. 4,438,221 which relates to the '220 patent describes polyurethane foam products having large amounts of inorganic filler materials other than combustion-retardant materials which can be used in various applications. Commonly assigned U.S. Pat. No. 4,683,246 discloses the use of a fibrous material as a specific filler material.
Although the products described in the aforesaid commonly assigned patents are highly useful and have excellent physical characteristics enabling their use for many applications, it has now been found that physical characteristics of foam products including compression set, stability, tear resistance, elongation, and tensile strength can be improved by incorporating into the foam certain organofunctional silanes.